Air cargo container and curtain for the same

ABSTRACT

A curtain closure for the cargo opening of an air cargo container and the air cargo containers that have the same. The curtain closures include a fabric layer, and at least one of an insulating layer or a reinforcing layer attached to the inside of the fabric layer.

FIELD OF THE INVENTION

The present disclosure relates to the field of transportation, and, moreparticularly, to cargo containers for aircraft. More particularly, thepresent disclosure relates to a fabric end closure for such containers.

BACKGROUND OF THE INVENTION

Cargo is typically transported in containers (“Unit Load Devices”),which are stowed in cargo holds either below the deck of passengeraircraft or below and above the deck in transport aircraft. The size andshape of Unit Load Devices vary depending upon the type of aircraft inuse. Typically, and regardless of the shape or geometry of thecontainer, one end or side of the cargo container is open for loadingand unloading cargo. Various door closures have been used for openingand closing the open ends of such containers. One type of closure hasbeen a rigid door closure which covers the opening to reduce tampering,to prevent the loss of small items, and to prevent the cargo from beingexposed to dirt, moisture, and ultraviolet light. Another type ofclosure includes a fabric closure or curtain. In all aircraft, the grossweight of the airplane is a substantial factor, because of the cost offuel. Even a slight reduction in weight is significant, therefore fabricdoors are often preferred.

Curtain closures for air cargo containers serve several purposes.Primarily, closures keep cargo contained inside of an air cargocontainer and minimize the unwanted intrusion into the air cargocontainer. Improvements have been made in curtain closures to increasetheir strength using high tenacity fibers to form the curtains. Thesecurtains have had the effect of lowering maintenance costs because thecurtains having high tenacity fibers may resist damage from the roughhanding common to air cargo containers. Particularly, sliding cargowithin the container is unlikely to puncture the high tenacity curtains.Further, curtains made from high tenacity fibers can resist puncturefrom cargo handling equipment such as fork lifts.

To further increase performance and reduce wear on the curtains,curtains for air cargo containers have been coated, laminated orimpregnated with materials such as ethylene vinyl acetate (EVA) torender the fabric curtains substantially waterproof and more highlyresistant to oils, gasoline, and other chemicals that may be present inan airport or other shipping environment. Even still, further advancesin performance can be made.

SUMMARY

Inventors have found that further improvements can be made to curtainsthat improve upon the tamper-resistance of the curtains. In otherinstances, improvements can be made in the ability for the curtain toinsulate the container with respect to temperature. In yet otherinstances, curtains can be improved both in their ability to insulateand their ability to avoid being accessed by an intruded, e.g. beingtampered with.

In one embodiment the present disclosure provides a fabric closure foran air cargo container, and the air cargo container having the same,wherein the fabric closure is a curtain formed of a fabric layer; and aninsulating layer attached to or incorporated into the inside of thefabric layer. The curtain may optionally include features to enhance thecut-resistance or fire-resistance of the curtain.

In another embodiment, the present disclosure provides a fabric closurefor an air cargo container, and the air cargo container having the same,wherein the fabric closure is a curtain having a fabric layer; and acut-proof reinforcing layer attached to or incorporated into the fabriclayer. The curtain may optionally include features to enhance thethermal insulation and fire-resistance provided by the curtain.

These and other aspects of the present disclosure will become apparentto those skilled in the art after a reading of the following descriptionof the preferred embodiments when considered in conjunction with thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of an air cargo container according tothe present disclosure.

FIG. 2 shows an exploded cross section of the curtain closure of thecontainer of FIG. 1.

FIG. 3 is an inside view of a metalized layer disposed on an insulatinglayer of the present disclosure.

FIG. 4 shows a detailed view of an optional venting feature of thecurtain closure of FIG. 1.

FIG. 5 shows the engagement between the curtain and the bottom wallaccording to one embodiment.

FIG. 6 shows the bottom of the curtain according to another embodiment.

FIG. 7 shows the bottom of the curtain engaged with the bottom wall ofthe container according to another embodiment.

FIG. 8 shows the bottom of the curtain engaged with the bottom wall ofthe container according to yet another embodiment.

FIG. 9 shows an exploded view of a suitable panel for the air cargocontainer of FIG. 1.

FIG. 10 shows a cross section of a suitable panel for the air cargocontainer of FIG. 1.

FIGS. 11-14 show containers and curtain closures of alternative shapeand accessibility.

FIG. 15 shows a cross section of a curtain closure according to anotherembodiment along representative line 15-15 in FIG. 1.

DETAILED DESCRIPTION

Exemplary embodiments of this disclosure are described below andillustrated in the accompanying figures, in which like numerals refer tolike parts throughout the several views. The embodiments describedprovide examples and should not be interpreted as limiting the scope ofthe invention. Other embodiments, and modifications and improvements ofthe described embodiments, will occur to those skilled in the art andall such other embodiments, modifications and improvements are withinthe scope of the present invention. Features from one embodiment oraspect may be combined with features from any other embodiment or aspectin any appropriate combination. For example, any individual orcollective features of method aspects or embodiments may be applied toapparatus, product or component aspects or embodiments and vice versa.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this disclosure belongs. The terminology used in thedescription of the embodiments herein is for describing particularembodiments only and is not intended to be limiting of the invention. Asused in the description and the appended claims, the singular forms “a,”“an,” and “the” are intended to include the plural forms as well, unlessthe context clearly indicates otherwise.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as density, weight, temperature, and soforth as used in the specification and claims are to be understood asbeing modified in all instances by the term “about.” Accordingly, unlessotherwise indicated, the numerical properties set forth in thespecification and claims are approximations that may vary depending onthe desired properties sought to be obtained in disclosed embodiments.

As used in the description and the appended claims, the phrase “unitload devices (ULDs)” also known as “air cargo containers,” is defined ascontainers used to load luggage, freight, mail, and the like onwide-body aircraft and some specific narrow-body aircraft.

Referring now to FIG. 1, there is illustrated an air cargo container orULD or simply container 100. Air cargo containers are designed to loadluggage, freight, and mail in aircraft, often in the lower deck area. Inthis regard, the cargo containers may be configured similar to the shapeof the aircraft. Some (LD1's-LD3's) are half-width and some (LD6) arefull width of the aircraft. The container 100 may include a frame 102presenting a generally rectangular shape with an offset designed to moreclosely follow the outline of the lower half of an aircraft. Thecontainer 100 may further include a cargo opening defined by a portionof the frame 102. The frame 102 may be formed from any substantiallyrigid material, such as aluminum, steel, composites, temperatureresistant plastics, other metals and non-metals.

The frame 102 may support a plurality of panels 104 forming the walls,and optionally the roof and floor of the container 100. In someembodiments, the panels 104 may be constructed together such that aseparate frame may be eliminated. The panels 104 may be preferably acomposite panel, as discussed below, for at least their lightweight,thermal insulating, and high strength characteristics. Alternatively,the panels 104 may also include aluminum, aluminum/Lexan composite,webs, fabrics, or some other light weight material. The cargo openingmay be substantially sealed, and selectively closed, by a door, referredto herein as a curtain 106, to reflect the flexible nature of doorsaccording to the present disclosure.

FIG. 2 shows an exploded cross sectional view of the curtain 106. Thecurtain 106 may include one or more exterior, outer layers 108, one ormore insulating layers 110, one or more reinforcing layers 112, and oneor more optional interior, inner layers 114. As used herein, the termsoutside and outer as used with respect to the interior and exterior ofthe cargo container 100. Therefore an inner layer of a curtain 106 wouldbe desirably, but not necessarily, facing into the container 100 whenthe curtain 106 is closed. The curtains 106 of the present disclosureinclude at least one of an insulating layer 110 or a reinforcing layer112. Some embodiments include both an insulating layer 110 and areinforcing layer 112. The reinforcing layer 112 may also be referred toas a cut-proof layer or a tamper-proof layer.

The outer layer 108 may be a conventional fabric sheet such as nylon,canvas, polyester, and other such materials. The fabrics are oftencoated with a water resistant or waterproof coating consisting of vinyl,polyethylene, neoprene, hypalon, or other such materials.

The outer layer 108 may, alternatively, be a high tenacity fabric layermade from at least 50% high tenacity fibers and preferably substantially100% high tenacity fibers. As used herein, the term “high tenacityfibers” means fibers which have tenacities equal to or greater thanabout 7 g/d. Preferably, the high tenacity fibers have tenacities equalto or greater than about 10 g/d, more preferably equal to or greaterthan about 15 g/d, even more preferably equal to or greater than about20 g/d, and most preferably equal to or greater than about 25 g/d.Examples of high tenacity fibers include highly oriented high molecularweight polyolefin fibers, particularly high modulus polyethylene fibers,highly oriented high molecular weight polypropylene fibers, aramidfibers, polybenzoxazole fibers such as polybenzoxazole (PBO) andpolybenzothiazole (PBT), polyvinyl alcohol fibers, polyacrylonitrilefibers, liquid crystal copolyester fibers, basalt or other mineralfibers, as well as rigid rod polymer fibers, and mixtures and blendsthereof. Preferred fibers may include high tenacity ultra-high molecularweight polyethylene (UHWMPE) fibers such as SPECTRA®, aramid fibers soldunder the trademarks Kevlar® or Nomex®, or liquid crystal fibers such asthose sold under the trademark Vectran®.

One example outer layer 108 may be a woven fabric formed from SPECTRA®ultra-high molecular weight polyethylene fibers. In one embodiment, thefabric preferably has between about 15 and about 45 ends per inch (about5.9 to about 17.7 ends per cm) in both the warp and fill directions, andmore preferably between about 17 and about 33 ends per inch (about 6.7to about 13 ends per cm). The yarns are preferably each between about650 and about 1200 denier. The result is a woven fabric weighingpreferably between about 2 and about 15 ounces per square yard (about67.8 to about 508.6 g/m2), and more preferably between about 5 and about11 ounces per square yard (about 169.5 to about 373.0 g/m2).

The outer layer 108 may be formed of a fire resistant fabric such as,for example, a woven fabric of basalt, carbon, or fiberglass fibers withan intumescent coating (soft char or harder char).

The outer layer 108 may include a protective layer 116 producing alaminated fabric. For example, the Spectra® fabric described above maybe coated or laminated with a thermoplastic film, to provide additionalprotection from the elements, such as waterproofing. As used herein, theterms “coated” and “laminated” may be used interchangeably to describeone or more protective layers 116 applied to a fabric substrate, such asthe outer layer 108. The protective layer 116 may be a thermoplasticfilm bonded to at least one side of the base fabric. The thermoplasticfilm may comprise ethylene vinyl acetate, high density polyethylene, lowdensity polyethylene, or a combination of the two. It has been foundthat polyethylene and ethylene vinyl acetate (EVA) films can be made toadhere to fabrics constructed from high tenacity polyethylene fiberswithout the use of a bonding agent under appropriate laminatingconditions.

In some embodiments, the temperature of the cargo within a ULD may bebetter maintained with a fabric closure designed with thermal insulationproperties in mind. For example, a relatively insulated fabric door mayextend how long the cargo is able to maintain a cool internaltemperature as an aircraft idles on the ground during a hot day waitingto take off. The insulating layer 110 may take a number of forms. In oneembodiment, the insulating layer may comprise one or more plies ofbubble film. The air present in the bubble film providing insulation,e.g. an increased R value, for the curtain 106 so that an initialtemperature within the container 100 may be maintained for longerperiods that comparable fabric doors without insulating layers 110.Suitable products may be available from Innovative Insulation, Inc., ofArlington, Tex.

Other materials that provide insulation, are lightweight, and maintainthe relative flexibility of the curtain 106 include silica aerogels,elastomeric films such as polyurethane or various rubbers, flexiblepolymer foams such as cross-linked polyethylene or polypropylene.Preferred insulation will not absorb meaningful amounts of water, andwill meet flammability specifications set forth by the appropriateAviation Authorities. An additional feature that may be incorporated inthe insulation layer 110 is using a fire resistant or suppressive foamproduct to contain interior fires and act as a fire block.

The insulating layer 110 may be incorporated as part of the curtain 106in a variety of ways. In one embodiment, the insulating layer 110 issewn to an inner surface of the outer layer 108. In other embodimentsthe layers may be laminated or otherwise bonded together.

In some embodiments, the insulating layer 110 may be covered by ametalized layer 118, such as a foil layer, as seen in FIG. 3. As isknown in the art, providing a reflective metalized layer 118 may furtherdecrease the ability for heat energy to pass through the insulatinglayer 110 or curtain 106.

Turning to FIG. 15, a cross section of a curtain 606 is shown accordingto another embodiment, the cross section taken along a line equivalentto 15-15 in FIG. 1. The curtain 606 includes an outer layer 108 and aninner layer 114 of flexible fabric as discussed above. A protectivelayer and a dedicated reinforcing layer may be optionally included. Theillustrated embodiment of the curtain 606 includes an insulating layer610 comprising a plurality of rigid panel segments 692 sandwichedbetween the outer layer 108 and the inner layer 114. The rigid panelsegments 692 may be constructed as discussed below with respect to thepanels 104, including a core 172 laminated between a pair of skins 174(FIG. 9). The number of panel segments 692 may vary to increase theflexibility of the curtain 606. For example, using a larger number ofsegments 692, each spanning a smaller portion of the height of thecurtain 106, would produce a more flexible door.

The illustrated construction of the curtain 606 provides for bendregions, or hinges 694, in between the panel segments 692 where theinner layer 114 and the outer layer 108 can come together and provide anarea where the curtain 606 may be folded. The hinges 694 may produce arelatively weak spot of the curtain 606. To increase security at theselocations, patches of the cut-proof reinforcing layer may be selectivelyprovided in areas of the curtain 606 corresponding to the hinges 694.One or more layers present at the hinges 694 may also be constructedfrom fire resistant materials to even further enhance the security ofthe curtain 606.

The use of rigid panel segments 692 enhances horizontal stiffness of thecurtain 606 when in the closed position to prevent bulging that could becaused by the weight of cargo within the container. As discussed above,the panels 104 (FIG. 9) have insulating properties, and therefore, whenused as the rigid panel segments 692, provide insulating properties tothe curtain 606. Rigid panel segments 692 constructed in accordance withthe panels are very strong, may be constructed to be fire resistant, andhave sufficient thickness to resist cutting with hand held implements.Therefore, adding rigid panel segments 692 as, or in addition to, theinsulating layer of the curtain 606 provides a high degree of securityat those locations of the panels similar to a reinforcing layer.

The configuration of the curtain 606 having hinges 694 and relativelyrigid panel segments 692 is not necessarily limited to the use ofcomposite panels consistent with the construction of the panels 104(FIG. 9). Instead, the relatively rigid panel segments 692 may berendered relatively rigid by a thick layer of insulating material. Forexample, the rigid panel segments 692 may comprise the rigid closed-cellfoam 172 without additional skins. Alternatively, the rigid panelsegments 692 may be relatively soft open-cell foam of sufficientthickness to resist substantial bending.

Returning to FIG. 2, some embodiments may include one or morereinforcing layers 112, particularly in embodiments including aprotective layer 116 applied to the exterior layer 108. The inventorshave found that the lamination of the high tenacity layers may have anegative impact on the curtain's resistance to being cut with shapeobjects, such as a box cutter.

The reinforcing layer 112 may comprise an uncoated fabric comprisinghigh tenacity fibers as discussed above with respect to optionalfeatures of the outer layer 108. A function of the reinforcing layer 112is to increase the slash-resistance of the curtain 106. One examplereinforcing layer 112 may be a dry woven fabric formed from SPECTRA®ultra-high molecular weight polyethylene fibers.

The inventors have found that a dry, uncoated fabric made fromhigh-tenacity fibers is significantly more resistant to beingintentionally cut or slit with a strong, sharp object such as abox-cutter. Inventors believe that the fibers and yarns in a dry weavehave significant individual give or movement within the fabric.Therefore, when a blade encounters a yarn in the uncoated fabric, theyarn will tend to deform or bend instead of being cut. On the otherhand, the coated fabric containing similar high tenacity yarns will bemore susceptible to being sliced open with a shape blade. The hightenacity yarns are bound together and made more rigid when the fabric orcoated or laminated. As a result, when the blade encounters each yarn,the yarns are stiffer and the blade is able to break through the yarnmore easily.

The inventors have discovered that the combination curtain 106 thatcombines a coated waterproof outer layer, e.g. because of a protectivelayer 116, with a dry uncoated reinforcing layer 112 on the inside ofthe waterproof layer forms a curtain 106 that significantly increasessecurity against being cut open while having the benefits of awaterproof layer on at least the outside. Therefore the combinationcurtain 106 provides benefits beyond the use of a coated or uncoatedfabric of high tenacity yarn alone. Though a dual layer curtain 106 willnecessarily weigh more than a single layer curtain, the increase inweight relative to the container 100 as a whole may be consideredmarginal for the increase in security of the disclosed curtains 106.

The uncoated high tenacity fabric is preferably sewn to the outer layeras an inward layer, but the uncoated high tenacity fabric could be usedas an outermost layer as well. By sewing the layers together, thepossible drawbacks of the protective layer 116 having coated the hightenacity fibers are not imparted upon the reinforcing layer 112 madefrom uncoated high tenacity fibers. Preferably, the reinforcing layer112 is present across substantially the entire area of the curtain 106.In other embodiments, the reinforcing layer 112 may selectively back theouter layer 108. In yet other embodiments, the reinforcing layer 112 maybe bonded to the outer layer 108. Bonding may occur at discretelocations spread throughout the area of the curtain 106. Each of thebonding locations may be only an inch or two in diameter. With thisapproach, even if the curtain 106 could be cut through and along alength of the bonding location, the resulting opening may besufficiently small to prevent passage of an intruder's hand.

In other embodiments, the reinforcing layer 112 may comprise a metalmesh. The mesh may be formed from metal wire comprising steel orstainless steel. The gauge of the mesh should be sufficient to resistbeing cut by handheld implements like knives, scissors, razor blades,etc., but not so large as to add significantly to the weight of thecurtain 106. In some embodiments a plurality of reinforcing layers 112may be included. Each of the plurality of reinforcing layers 112 may besubstantially similar or each may have a different structure. Forexample, a curtain 106 may include an uncoated fabric of high tenacityyarn and a layer of metal mesh.

Where the reinforcing layer 112 comprises a metal mesh, the reinforcinglayer may be bonded or laminated to the outer layer 108. For example, anEVA film may bond the metal mesh to an inner surface of the outer layer108.

The optional inner layer 114 may be a fabric layer substantially similarto the outer fabric layer 108 with or without the addition of one ormore protective layers 116.

Returning to FIG. 1, the curtain 106 may be provided with a hem alongthe top and both sides thereof through which metal strips extend. Holesmay be drilled through the metal strip at spaced points andcorresponding apertures provided in the fabric in both folds of the hem.Rivets may then attach the sides and top to adjacent panels 104 orportions of the frame 102. As discussed below, other embodiments mayattach the curtain 106 to the container 100 using less permanentmethods, such as using the combination of web straps and releasablefasteners.

The curtain 106 may include a pair of spaced apart vertical openings 120extending from a bottom edge 122 of the curtain 106 to a point adjacentto, but spaced slightly from the edge of a top wall of the container100. A slide fastener 124 may extend along the adjacent edges of each ofthe vertical openings 120. The slide fasteners 124 should be at leastabout 10 gauge. Slide fasteners 124 may be a preferred method of sealingthe selectively openable vertical openings 120 because the slidefasteners 124 highly restrict the ability for air to pass through aclosed vertical opening. For insulation purposes, limiting the abilityfor air to travel between the interior and exterior of the container 100improves the ability for the container to maintain its initial internaltemperature when loaded with cargo. However, the slide fastener 124 maypresent an area of weakness for the curtain 106. Preferably, the slidefastener 124 may have similar cut-resistant properties as the rest ofthe curtain 106. In one example, the tape of the slide fastener 124 maybe an uncoated woven material constructed of high tenacity fiberssimilar to one embodiment of the reinforcing layer 112. Those hightenacity fibers may be of the fire resistant type, such as basalt,carbon, or fiberglass fibers to help contain an internal fire.

The curtain 106 may be further provided with stiffening strips 126 sewnin or otherwise affixed to one surface thereof, as for example, in theX-pattern shown. Other patterns are also possible. For purposes ofpressure equalization, as seen in FIG. 4, vent holes 128 may be addedthrough the curtain 106. A cover 130 may be sewn onto the curtain 106 tolimit air passage through the vent holes other than due to pressureequalization. Limiting movement of air from inside the container tooutside the container will help maintain the internal temperature of thecontainer 100 as desired by embodiments of the present disclosure. Thecover 130 may be sewn along three sides with the bottom left open forventilation. The cover 130 may be formed from one or more of the layerspresent in the curtain 106.

Turning to FIGS. 5-8, tightly securing the bottom edge 122 of thecurtain 106 to the container 100 may be important for several reasonsincluding: prevention of unwanted intrusion into the container,prevention of small cargo items escaping the container, and preventionof significant transfer of air that can significantly impact the abilityto maintain the internal temperature of the container 100.

As seen in FIG. 5, cargo containers often include a front rail 132 witha T-slot 134 therein. The bottom edge 122 of the curtain 106 may beprovided with a plurality of cleats 136 which may be riveted orlock-bolted through the curtain 106 adjacent the bottom edge 122thereof. For reinforcement the bottom edge 122 may also be formed by ahem through which a thin strip (¾″× 3/16″ for example) of fiberglasscomposite, carbon composite, aluminum, or other light weight metalextends. The strip distributes the load between the cleats 136. Thecleats 136 are formed of some appropriate strong hard polymeric ormetallic material and include a base portion 138 and a locking portionin the form of a pair of circular members 140 extending downwardlytherefrom. The locking portion (circular members 140) is secured to thebase portion 138.

Two or more sets of two bores 142 are provided through the top wallforming the T-slot 134 which receives the circular members 140 of thecleats 136, which are so sized and shaped as to ride easily in theT-slot 134. Once in the track, movement of the cleats 136 along thetrack in such a manner that the circular members 140 are no longeraligned with the bores 142 will retain the bottom edge 122 of thecurtain 106 in place.

Security may be increased further by providing any one of a variety oflocks to prevent the undesired or unidentified opening of the curtain106. In one example shown in FIG. 6, the slide fasteners 124 may be ofthe locking type that includes a tab 144 and a loop 146. When the tab144 is lifted upwardly, the zipper slide 148 is locked and cannot bemoved. The loop 146 extends through the tab 144, and when a wire 150 isinserted therethrough, the tab 144 cannot be lowered. The wire 150 maylead to a pin 152 attached thereto. A hole 154 may extend through theopposite end of the pin 152. The cleat 136 may include an L-shapedflange 156 extending outwardly therefrom. An opening in the flange 156may receive the pin 152. When a security tag (FIG. 8) or combinationlock is inserted in the hole 154, the cleat 136 is limited in itsmovement along the T-slot (FIG. 5), and the length of the wire 150 issuch that the cleat 136 cannot be moved back to a position where thecircular members 140 are aligned with the bores 142 (FIG. 5).

FIG. 7 shows another lock embodiment where the cleat 136 includes anenlarged boss 158 at the end adjacent to a slide fastener of the curtain106. A channel through the boss 158 may receive a spring-loaded detentpin 160. The front rail 132 may include a slot that receives the detentpin 160 when the cleat 136 is inserted in the T-slot and moved to theseated position.

FIG. 8 shows yet another lock embodiment for securing the bottom edge122 of the curtain 106 in the closed position. The bottom edge 122 ofthe curtain 106 may include a rigid (preferably hollow) bar receivedinto a hem in the fabric itself. The bar is preferably a carbon fiberbar, selected because of its light weight, but could also be aluminum orother material. On one end of the bar is a spring loaded pin 162 thatfits into a hole in an angle bracket 164 welded or otherwise attached tothe front face of the container frame 102. The spring loaded pin 162 maybe released by a spring loaded handle 166, which, when retracted, allowsthe spring loaded pin 162 to be removed from the hole in the anglebracket 164. The handle 166 may be provided with a transverse hole 168.A security tag 170 may extend through the transverse hole 168 in thehandle 166 and either through the angle bracket 164 or through a portionof the zipper slide 148.

Referring now to FIG. 9, an exploded view of an example panel 104 isshown. The panel 104 includes a core 172 and a skin 174 attached in someappropriate manner to each surface thereof.

The core 172 may include foam 176. The foam 176 may be a fire resistantfoam having a density between 0.75 lbs./ft3 (pcf) to 20 pcf, however, adensity of between 1.9 pcf and 7.4 pcf is preferred. Densities over 20pcf would work well as a structural core and as an insulation material,but weight of the final product then becomes more of a question andperhaps prohibitive. The typical foam used in composite construction isa closed-cell foam. Because liquid resin is often used in theconstruction and/or bonding materials, it is important that the foam 176be unable to “soak up” the resin. The closed-cell foam provides enoughsurface “roughness” for excellent bonding without allowing resin toimpregnate the core 172. Example foams include phenolic foam, carbonfoam, or ceramic foam. Other polymeric foams may also be used,especially if fire resistance is not critical.

Any thickness of foam 176 can be used to create the core 172. For thepresent application, the foam 176 acts as a thermal insulator. In thepresent application, it is anticipated that foam thickness willpreferably fall between the values of 0.25 inches-2.0 inches for themajority of containers, but slightly greater thicknesses are possible.It will be appreciated that the thicker the foam, the greater the degreeof thermal insulation.

The core 172 may also include a honeycomb matrix 178. The combination ofthe honeycomb matrix 178 and the foam 176 provides the high compressiveand shear strength characteristics of a honeycomb with the insulationproperties and bonding surface area of closed-cell foam. Thisconstruction tends to be of a higher density than foams alone. A typicalconstruction for this application might be a phenolic paper/clothhoneycomb with cells filled with phenolic foam.

The skins 174 may be formed of fibers embedded in a resin that binds thefibers together. Suitable fibers may include fiberglass, basalt/mineralfibers, aramid cloth, mat and non-wovens (known as Nomex, Kevlar,Technora and others), carbon fibers, ceramic fibers or quartz fibers.

By way of example, the fibers can be laid up in a unidirectionalpattern, can be woven, knit or formed as a non-woven web. Bulkproperties are then generated by the number of layers and the fiberangle of each layer compared to the other layers. The thickness of theskin 174 can be discretely changed by varying the number of layers, orby the thickness of each individual layer, or by a combination of both.All layers can be of the same fiber material or can be of differentfiber blends.

The resin is used to bind the fibers together to form the rigid skins174. The resin may include phenolic, polyimides including bismaleamides,epoxies, polyesters, and vinyl esters. The resin may also includepolyphenylene sulfide and similar sulfides, polyether imide, polyamideimide, and polyetheretherketone.

The skins 174 and core 172 may be secured or attached together invarious ways. For example, the skins 174 may be adhered to the core 172by the resin. In another example seen in FIG. 10, Z-axis fibers 180 areinserted through the skins 174 and the core 172. This approach of areinforced composite is illustrated in at least U.S. Pat. No. 8,002,919.The Z-axis fibers 180 are impregnated with resin during themanufacturing process. The Z-axis fibers 180 serve to preventdelamination.

Turning to FIGS. 11-14, various alternative configurations of containersand fabric closures are shown that may include curtains having thelayers described with respect to FIG. 2. In other words, curtains havinga structure as discussed with respect to the layers of FIG. 2, may becreated to match any of the additional embodiments shown in FIGS. 10-13and others known to other of ordinary skill in the art.

FIG. 11 shows a container 200 of an alternative configuration with acurtain 206 sized to completely cover the open end thereof and tooverlap the side and top edges thereof. The edge portion may beconfigured to provide an additional barrier to environmental or otheranticipated undesirable elements as described in U.S. Pat. No.6,755,232. The curtain 206 is shown as a unitary construction withoutthe vertical openings or slide fasteners used in the curtain of FIG. 1.

A plurality of opposed web straps 282 may be attached to the top andbottom portions of the curtain 206. Similarly, opposed web straps may beattached to opposing side portions of the curtain. The web straps 282may be formed from nylon, but other high strength webbing materials maybe substituted. The term “high strength webbing” material means webbinghaving a tear strength of about 400 pounds or more per linear inch ofwebbing width. The web straps may be sewn to the curtain 206 with highstrength threads such as SPECTRA®, or DYNEEMA®, available from DSM.

A variety of fasteners 284 are commercially available for attachment tothe web straps 282. The choice of fasteners may be dependent upon thespecific container, government regulations regarding transportation ofspecific containers, and the particular application.

FIG. 12 shows a container 300 with a curtain 306 with a substantiallyvertical opening 320 extending substantially the height of the curtain.The vertical opening 320 separates the curtain in two portions. Thevertical opening 320 may be secured by both web straps 382 and fasteners384 as well as a slide fastener (i.e. a zipper) 324. As will beappreciated, the slide fastener 324 that is attached along the verticalopening 320 separates from the bottom edge 322 of the curtain 306upwardly, and interlocks from the top edge of the vertical opening 320downwardly. Suitable slide fasteners 324 should be at least about 10gauge, as “gauge” is commonly measured in the art, to provide theheavy-duty load restraint needed.

Optionally, to protect the slide fastener 324 from contamination andexposure from the elements, a flap 386 may be affixed to the curtain 306by sewing, adhering, etc. to extend along the length of the verticalopening 320, the flap 386 has one edge permanently attached to thecurtain 306 and an opposed free edge overlying the slide fastener 324.To further protect the slide fastener 324 from contaminants andenvironmental exposure, the flap 386 may be secured down with a hook andlook fastener 388, such as VELCRO®.

In some embodiment, the slide fastener 324 may present a location on thecurtain 306 that is most susceptible to conductive heat transfer becauseof the slide fastener's materials and requirement to form a thin spot inthe thickness of the curtain 306. The flap 386 may increase insulationat this location. In other embodiments, a flap may be placed along theinside of the curtain 306 instead of or in addition to the flap 386. Theflap 386 may be constructed from one or more the of same layers as thecurtain 306. For insulation purposes, the flap 386 should include theinsulating layer 110.

Turning now to FIG. 13, a curtain 406 is shown with a selectivelycloseable access opening formed in a T-shape with a substantiallyvertical opening 420, having a length extending from the bottom edge 422of the curtain 406 to a point spaced apart from the top edge thereof,and a substantially horizontal opening 490 having two horizontalportions that each extend from a point spaced from an opposed side edgeof the curtain toward the center thereof to intersect at the upper edgeof the vertical opening 420. A slide fastener 424 may be attached alongeach opening. As will be appreciated, the slide fastener that isattached along the vertical opening 420 separates from the bottom edgeupwardly. The other slide fasteners separate from the intersection withvertical opening outwardly toward the opposed side edges of the curtain.The curtain 406 may include web straps 482, fasteners 484 and flaps 486similar to the curtain 306 shown in FIG. 12.

Yet another embodiment, a curtain 506 is shown in FIG. 14 that issubstantially similar to the curtain 406 of FIG. 13, but with a verticalopening 520 and a horizontal opening 590 forming an L-shape.

Although the above disclosure has been presented in the context ofexemplary embodiments, it is to be understood that modifications andvariations may be utilized without departing from the spirit and scopeof the invention, as those skilled in the art will readily understand.Such modifications and variations are considered to be within thepurview and scope of the appended claims and their equivalents.

What is claimed is:
 1. A curtain closure for a cargo opening of an aircargo container, said curtain closure comprising: a coated exteriorfabric layer rendering the curtain closure substantially waterproof; areinforcing layer comprising an uncoated fabric layer consistingessentially of fibers having a tenacity greater than about 20grams/denier; and a thermal insulating layer to help maintain aninternal temperature of the air cargo container, the thermal insulatinglayer further comprising a metallized layer for heat reflection on aninterior side of the thermal insulating layer.
 2. The curtain of claim1, wherein the exterior fabric layer comprises: fibers having a tenacitygreater than about 20 grams/denier.
 3. The curtain of claim 1, whereinthe thermal insulating layer is sewn to an inner surface of the exteriorfabric layer.
 4. The curtain of claim 1, further comprising an innerfabric layer, wherein the thermal insulating layer is provided insegments such that the curtain comprises a plurality of relatively rigidsegments having a portion of the thermal insulating layer disposedbetween the inner fabric layer and the exterior fabric layer, theplurality of relatively rigid segments separated by flexible hingeportions comprising at least the inner fabric layer and the exteriorfabric layer.
 5. The curtain of claim 1, further comprising vent holesand a cover provided over the vent holes.
 6. The curtain of claim 1,wherein the reinforcing layer is sewn to the exterior fabric layer. 7.The curtain of claim 1, wherein the thermal insulating layer incudes airconfigured to provide insulation.
 8. The curtain of claim 1 furthercomprising at least one vertical opening selectively closeable by aslide fastener.
 9. The curtain of claim 8 wherein a tape of the slidefastener is made from an uncoated fabric layer consisting essentially offibers having a tenacity greater than about 20 grams/denier.
 10. Thecurtain of claim 8 wherein a tape of the slide fastener is made from afire-resistant material selected from the group consisting of basalt,carbon, and fiberglass.
 11. The curtain of claim 8, wherein the curtainfurther comprises a lock to maintain the slide fastener and the curtainin a closed position.
 12. An air cargo container, comprising: a frame; aplurality of walls, wherein the walls comprise wall panels, each panelcomprising an insulating foam core sandwiched between a pair of skins;and a selectively openable curtain closure according to claim 1,positioned to substantially seal the cargo opening when the curtainclosure is in a closed position.
 13. The air cargo container of claim12, wherein the curtain further comprises vent holes and a coverprovided over the vent holes.
 14. The air cargo container of claim 12,wherein the curtain further comprises at least one vertical openingselectively closeable by a slide fastener.
 15. The air cargo containerof claim 14, wherein a tape of the slide fastener is made from anuncoated fabric layer consisting essentially of fibers having a tenacitygreater than about 20 grams/denier.
 16. The air cargo container of claim14 wherein a tape of the slide fastener is made from a fire-resistantmaterial selected from the group consisting of basalt, carbon, andfiberglass.
 17. The air cargo container of claim 14, wherein the curtainfurther comprises a lock to maintain the slide fastener and the curtainin a closed position.
 18. A curtain closure for a cargo opening of anair cargo container, said curtain closure comprising: a coated exteriorfabric layer rendering the curtain closure substantially waterproof; areinforcing layer comprising an uncoated fabric layer consistingessentially of fibers having a tenacity greater than about 20grams/denier; and a thermal insulating layer to help maintain aninternal temperature of the air cargo container, wherein the thermalinsulating layer comprises a bubble film.
 19. A curtain closurecomprising: a substantially waterproof coated fabric layer; areinforcing layer comprising an uncoated fabric layer including fibershaving a tenacity greater than 20 grams/denier; and a thermal insulatinglayer configured to thermally insulate one side of the curtain closurefrom the other side of the curtain closure, the thermal insulating layerselected from the group consisting of: bubble film, aerogels, flexiblepolymer foams, and elastomeric films.